The population 85 years and over may well number 12.8 million in the U.S. by the year 2040. This aging of the elderly will have dramatic economic and social effects on American society. It is only recently that attention has focussed on this phenomenon, and relatively few detailed and reliable data concerning this population are available. The proposed research consists of a series of follow-on studies of the extreme aged and is intended to add important new dimensions to a comprehensive monograph on the demographic characteristics of America's fastest growing sub-population. This additional series of studies will investigate significant issues raised during the preparation of the monograph but which could not be explored in depth, given the time constraints of the project. Four specific studies are planned: 1) To examine the reliabiity of the post-1980 Census Bureau estimates of the 85-and-over population. These are critical figures as they are used to calculate official mortality rates; 2) To examine differentials in childlessness and marital status between the institutionalized and noninstitutionalized aged, utilizing 1970 and 1980 census microdata samples. Analysis of the role of cohort effects will be of great value in making nursing home population projections; 3) To determine the utility of the 1980 census item on public transportation disability. Given what gerontologists have called "the poverty of health data on the aged in the 1980 census," this investigation will help determine whether this less-than-perfect query may yet be of considerable value; 4) To consider the growth of the extreme aged in the U.S. in an international context. Demographic trends and patterns in the U.S. will be compared with those in France, the "first aged country." These comparisons may help distinguish between factors inherent to the aging process per se and those specific to the socioeconomic and health policies of the two nations.